The present invention relates to a device for controlling a position sensor of a motor vehicle fitted with a power-steering motor.
The vehicles of today are fitted increasingly frequently with a power-steering motor. Such vehicles comprise a steering system formed by a steering column supporting at its top end a steering wheel capable of being actuated by the driver of the vehicle, a rack on which the bottom end of the steering column acts and a power-steering motor mechanically connected to the rack. An electronic management system of the ECU (electronic control unit) type controls the power-steering motor in order to prevent the steering of the vehicle becoming too light at normal speed or too heavy at virtually zero speed.
For the correct operation of the power-steering motor, it is necessary to have an item of information reflecting the angular position of the steering wheel in order to perform the function of automatic return of the steering wheel. This information is usually supplied by a steering-wheel sensor situated on the steering wheel. The presence of a steering-wheel sensor dedicated to this function however causes a considerable extra cost.
The angular position of the steering wheel of a vehicle may also be obtained by virtue of a position sensor situated on the power-steering motor.
However, the use of this type of sensor poses certain problems. Specifically, the position of the steering wheel must be known at all times (i.e. when stationary and when running). Accordingly, it is necessary to keep the position sensor of the power-steering motor powered up even if the ignition of the vehicle is switched off. Keeping powered up in this way causes a risk of discharging the battery.
In this context, the object of the invention is to remedy the aforementioned problems of the prior art by proposing a device capable of determining, when the ignition of the vehicle is switched off, the angular position of the steering wheel, with precision and exactitude, while ensuring minimum electrical consumption and while preventing a risk of discharging the battery of the vehicle.